1. Field of the Invention
The present invention relates to an actuator. More particularly, the present invention relates to an actuator in which either a unidirectional adjusting device for adjusting an irradiating direction of light from a light source of a lamp unit in a single direction or a bidirectional adjusting device for adjusting the irradiating direction in two directions is selectively installed, so as to ensure a versatility of the actuator without causing an increase in manufacturing costs thereof.
2. Related Art
In vehicle headlamps, there are, for example, vehicle headlamps in which a lamp unit having a light source and a reflector for reflecting light from the light source is disposed in an interior of a lamp casing which is made up of a cover and a lamp housing.
In these vehicle headlamps, there is a vehicle headlamp of a type in which the lamp unit is supported rotatably (or in a tilting fashion) on a support member such as a frame or a bracket so that the lamp unit is rotated by virtue of driving force of an actuator (refer to Patent Documents 1 to 3, for example).
[Patent Document 1] JP-A-2007-128856
[Patent Document 2] JP-A-2008-094275
[Patent Document 3] JP-A-2008-123855
In the vehicle headlamp of the type, a so-called leveling adjustment (a leveling operation) is performed in which a deviation of an optical axis of the lamp unit is adjusted by rotating (tilting) the lamp unit in a vertical direction by the actuator when the optical axis of the lamp unit changes to deviate from a predetermined level due to a weight of a load on a vehicle. In addition, a so-called swiveling adjustment (a swiveling operation) is performed in which the direction of the optical axis of the lamp unit is changed so as to follow a traveling direction of the vehicle.
However, there are some vehicle headlamps which do not need a swiveling adjustment function but need a leveling adjustment function only.
In this case, in the event that the actuator which has both the swiveling adjustment function and the leveling adjustment function is used, a structure for an unnecessary function becomes wasteful, eventually calling for an increase in manufacturing costs of the actuator.
On the other hand, in the event that an actuator having only a leveling adjustment function is fabricated, the actuator cannot be adapted to a vehicle headlamp which needs both the swiveling adjustment function and the leveling adjustment function. To complete such vehicle headlamp, a structure exclusive to the leveling adjustment is needed separately, which increases the manufacturing costs accordingly and makes it impossible to ensure the versatility of the actuator.